Simplify the following expression: $y = \dfrac{-9}{3k} - \dfrac{9}{3k}$
Answer: Since the expressions have the same denominator we simply combine the numerators: $y = \dfrac{-9 - (9)}{3k}$ Combine like terms: $y = \dfrac{-18}{3k}$ Simplify by dividing numerator and denominator by 3: $y = \dfrac{-6}{k}$